pretzel: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/pretzel - from package: pretzel

You may install the required package with command apt-get install {package}

Error in other languages:
pretzel: bevel nie gevind nie
pretzel: comandă negăsită
pretzel: comando não encontrado
pretzel: commande introuvable
pretzel: command not found
pretzel: käsku ei ole
pretzel: không tìm thấy lệnh
pretzel: komanda nerasta
pretzel: Kommando nicht gefunden.
pretzel: kommandot finns inte
pretzel: komut yok
pretzel: nie znaleziono polecenia
pretzel: níor aimsíodh an t-ordú
pretzel: no se encontró la orden
pretzel: no s'ha trobat l'ordre
pretzel: opdracht niet gevonden
pretzel: parancs nem található
pretzel: perintah tidak ditemukan
pretzel: príkaz nenájdený
pretzel: příkaz nenalezen
pretzel: команда не найдена
pretzel: командата не е открита
pretzel: 命令找不到
pretzel: コマンドが見つかりません